Corsair CM3X4GSD1066 RAM Module - 4 GB - DDR3 SDRAM - 1066 MHz DDR3-1066/PC3-8500 - Unbuffered - 204-pin SoDIMM. When you buy Crucial memory, you're buying directly from the largest DRAM manufacturer in America and one of the top three in the world. Crucial Technology is a division of Micron. We have more than 20 years of industry experience and are the lowest-cost, most efficient DRAM manufacturer, and many of the world's leading computer manufacturers use our memory. Crucial brings that same high-quality memory directly to you, the end consumer.